Experiments on mice show that feeding them protein from certain environmentally sound bacteria can both boost the immune system and prevent the mice (and perhaps also people) from gaining weight.
The prospect of more than 10 billion people on the planet means that not everyone can expect steak, chicken or fish for dinner.
Some people will need to derive their protein from other sources, and one healthy choice may involve protein from certain bacteria.
A new international study shows that feeding mice protein from Methylococcus capsulatus Bath boosts the mice’s immune system and causes them to lose weight.
The main author behind the study, Benjamin Anderschou Holbech Jensen, postdoctoral fellow, University of Copenhagen, thinks that eating bacteria as a protein source or as a dietary supplement may prevent people from gaining weight and developing several related diseases.
“We only need to change the protein source in the food for the mice to become healthier and stop gaining weight. This is like continuing to eat food from McDonald’s but without experiencing the unhealthy effects because the protein comes from bacteria instead of beef,” explains Benjamin Anderschou Holbech Jensen.
The research has been published in Nature Communications.
Gut microbes are the key to health
The background to this remarkable result is the importance of gut microbes.
Trillions of bacteria from hundreds of species live in the intestines of all people and animals, and some promote health and others do not.
An unhealthy composition of gut microbes is associated with developing a wide range of metabolic, inflammatory, autoimmune and even nervous system disorders and is strongly associated with developing obesity.
Conversely, having the right amount of the right bacteria in the gut can promote health.
Mice ate unhealthy food and still lost weight
In the research, Benjamin Anderschou Holbech Jensen and his colleagues investigated what happens to mice fed protein from M. capsulatus Bath, which usually does not live in the intestines of mice or humans but is present in soil.
The researchers freeze-dried the bacteria to destroy the cell walls so the mice could access the protein and other nutrients from the bacteria.
The researchers fed the mice a standard Western diet for a few weeks largely comprising a protein source, a fat source and a carbohydrate source in varying ratios, corresponding to daily visits to a burger bar.
When the mice became obese and began to display signs of metabolic syndrome, the precursor to developing type 2 diabetes, the researchers replaced the protein source in the diet with protein from the bacteria. The rest of the diet remained a standard Western diet that in all respects would make the mice continue on their unhealthy trajectory.
“The mice continued to be fed a diet high in fat and sugar, but the protein source was replaced by French-pressed bacteria. French press is known from coffee production to extract flavour and nutrients from the beans. When used on bacterial matter, we generate a lysate of inactivated and dead bacteria with disrupted cell walls. This is important for two reasons: dead bacteria will not compete with the commensal microbes for space and nutrients and a disrupted cell wall is needed before non-ruminants, such as mice and humans, can digest bacteria-derived intracellular nutrients,” says Benjamin Anderschou Holbech Jensen.
Mice lost weight and had healthier immune responses
The results of the experiments were surprisingly clear.
· The mice became metabolically healthier in a few weeks and exhibited modestly improved insulin sensitivity and greater glucose tolerance. Their weight also stabilized.
· The composition of their gut microbiota also promoted their metabolic and immune health.
Benjamin Anderschou Holbech Jensen and colleagues suspect that one reason the immune response improves is that the content of the French-pressed bacteria promotes beneficial bacterial strains, including Parabacteroides, in the gut microbiota. In any case, the researchers found that the number of Parabacteroides increased sharply in the mice fed bacterial protein.
The induction of Parabacteroides depended on the acquired immune response, which also changed when the mice were fed M. capsulatus Bath.
The researchers also discovered increased production of some regulatory T cells, which help to keep the gut healthy and counteract food allergies.
“Our partners carried out experiments on mice that induced ulcerative colitis, and the new diet counteracted this,” explains Benjamin Anderschou Holbech Jensen.
Boosting the creation of immune cells
Benjamin Anderschou Holbech Jensen says that, although the experiments have only been performed on mice, he hopes that the results can be transferred to people.
He does not think that the world’s burger chains are going to replace beef in their burgers with bacteria, but he hopes that future research can identify the bioactive molecules in M. capsulatus Bath that cause the beneficial effect.
If researchers can identify them, they can also test them as possible dietary supplements for people.
“We need to find the doses that are physiologically relevant to steer changes in the human gut towards promoting health. Affecting the regulatory T cells and thus counteracting food allergies is also an interesting perspective and worth exploring further,” says Benjamin Anderschou Holbech Jensen.
Growing bacteria using greenhouse gases in large tanks
An entirely different aspect of the research is M. capsulatus Bath, which is not present in the gut but in soil, in which it derives energy from methane.
Methane is a powerful greenhouse gas, and the bacteria can therefore be used both to make people healthier and to improve the environment.
The bacteria can be grown in large tanks, and the researchers have just initiated fruitful collaboration with a company that specializes in fermenting methane with bacteria and are taking the next step of commercializing the process.
“The bacteria promote health and improve the environment in contrast to protein from animal and even plant sources. The need for protein alternatives will be huge, and we think that bacteria can become a big hit,” concludes Benjamin Anderschou Holbech Jensen.